The present invention relates to a system for disinfection, purification and deodorization, using a gaseous phase containing ozone. More particularly, the invention relates to said system, wherein the above operations are carried out on the surface of the respective objects to be treated.
The disinfection treatment with ozone of solid objects, such as fresh agricultural produce, drugs and medical and industrial equipment, is well known, being carried out in a gaseous form or in an aqueous solution. Among the main disadvantages of this treatment for agricultural produce the following can be mentioned:
(a) Possible damage to certain kinds of agricultural produce due to interaction with the surface of the treated material and,
(b) Diffusion of ozone into the treated tissue. in case of non-agricultural solid objects, such as: drugs as well as food products, the following can be mentioned:
(c) There are parts on the objects to be treated where there are stagnant regions, i.e. no free flowing gas, so that the ozone penetration is inefficient.
Among the disadvantages of treatment in a liquid phase, the following can be mentioned:
(a) It is impractical to wet the products to be treated and then to dry them again.
(b) There are products, the surface of which may be affected after their immersion in a liquid, the surface area may be affected. Thus, the cuticle coating the egg shell may dissolve in an aqueous solution and as a result the treated egg may lose a large amount of water during subsequent storage.
(c) Metallic parts may undergo corrosion after the treatment in a liquid phase.
(d) Fruits and vegetables possessing a plume may lose it and as a result, become less attractive.
The importance of the above problem, is evidenced by the relatively large number of patents and papers dealing therewith. Thus, according to Chemical Abstract Vol.123: 8355. an apparatus is disclosed for sterilization of food by its immersion in water, where a stream of ozone and air is bubbled continuously into the water.
According to the recent U.S. Pat. No. 5,403,602, the process utilizes an aqueous solution containing 3% to 12% ozone. The released ozone reacts with the food constituents, being controlled by the introduction of an enzyme catalyst. This sterilization process is claimed to be most useful for aseptic packaging of fresh food.
According to Chemical Abstract Vol.119:15419, an apparatus is described for sterilizing fluids, consisting of an ozone chamber in which ozone is generated and then dispersed throughout the ozone-air mixture by a diffuser. The fluid and ozone are thoroughly mixed in a chamber and radiates the fluid to be treated. As claimed this apparatus is useful for food processing, farming and water or air purification plants.
According to Chemical Abstract Vol.116:261655, odorous air or water in refrigerating cases used for displaying fish and other foods, is deodorized by injecting ozone in a system comprising means for gaseous or liquefied ozone in a pressure vessel connected to the refrigeration cases. It is stipulated, that bacterial growth and malodor formation inside the refrigeration cases can be significantly lowered.
According to Chemical Abstract Vol.116:234256, a method and apparatus are described for sterilizing vegetables and fish using an aqueous ozone solution at a pH in the range of 3.5-4.5. This pH range is maintained by addition of an organic acid, such as acetic acid, the ozone solution controlling the microorganisms growth.
The above brief review clearly illustrates the existence of the problem and need for disinfection, purification and deodorization of fresh agricultural produce, drugs, and medical and industrial equipment using ozone.
It is an object of the present invention to provide a system for disinfection, purification and deodorization of the objects kept in a treatment space, using ozone. It is another object of the present invention to provide a system for disinfection, purification and deodorization of said objects, which overcome the existing drawbacks of the known systems.
A first aspect of the present invention relates to a system for disinfection, purification and deodorization of the surface of objects kept in a treatment space. by a forced stream of gaseous ozone mixed homogeneously with a carrier gas, flowing on the said surface, said flow being assisted by acoustic waves.
According to a preferred embodiment, the acoustic waves are produced through an acoustic transducer.
Thus, according to the teachings of the present invention there is provided, a frame-type ozone generator comprising: (a) a plurality of elongated electrodes deployed in substantially parallel, spaced relation to each other so as to form a substantially flat electrode array; and (b) a flow generator for generating a flow of oxygen containing gas through the electrode array in a direction substantially perpendicular to the electrode array, wherein each of the electrodes is formed from an electrically conductive core covered with polyvinyl-difluoride.
According to a further feature of the present invention, the electrode array is arranged within a frame of a given area, the frame being configured for assembly with other similar frames to form an extended ozone generator of area greater than the given area.
According to a further feature of the present invention, the frame is substantially rectangular having first and second sides substantially perpendicular to the electrodes, the first and second sides being formed with complementary interlocking forms such that the first side could be engaged with a juxtaposed second side of a similar frame to form an extended ozone generator unit.
According to a further feature of the present invention, the first side includes a first common electrical connection to a first set of the electrodes, the complementary interlocking forms being configured such that the first common electrical connection would make electrical contact with another common electrical connection of a similar frame juxtaposed so as to interlock with the frame.
According to a further feature of the present invention, the frame has first and second ends substantially parallel to the electrodes, the first and second ends being formed with complementary interlocking shapes such that the first end could be engaged with a juxtaposed second end of a similar frame to form an extended ozone generator unit.
According to a further feature of the present invention, the first end includes a first common electrical connection to a first set of the electrodes, the complementary interlocking shapes being configured such that the first common electrical connection would make electrical contact with a common electrical connection of a similar frame juxtaposed so as to interlock with the frame.
According to a further feature of the present invention, the frame and the electrode array are integrally formed from molded polyvinyl-difluoride with electrically conductive implants.
There is also provided according to the teachings of the present invention. an apparatus for treating a product with ozone-containing gas, the apparatus comprising: (a) a container for containing the product; (b) an ozone generator for supplying ozone-containing gas to the interior of the container; and (c) a pressure-wave generator for generating pressure waves within the container so as to enhance effectiveness of the ozone treatment.
According to a further feature of the present invention, there is also provided a flow generating system for generating circulation of the ozone-containing gas.
According to a further feature of the present invention, there is also provided a flow generating system configured so as to generate a flow of the ozone-containing gas which alternates between a first direction and a second direction opposite to the first direction.
According to a further feature of the present invention, there is also provided a flow generating system configured so as to generate simultaneous flows of the ozone-containing gas in more than one direction towards the product.
According to a further feature of the present invention, there is also provided a cooling system for cooling at least a surface layer of the product prior to treatment sufficiently to cause condensation of ozone-containing water vapor on the surface layer.
According to a further feature of the present invention there is also provided a cooling system for cooling at least a surface layer of the product prior to treatment sufficiently to cause freezing of ozone-containing water vapor on the surface layer.
According to a further feature of the present invention, the product is water. the apparatus also including a water management system for generating a moving film of water within the container.
According to a further feature of the present invention, the product is water, the apparatus also including: (a) a spray generator for producing a spray of water moving in a first direction within the container; and (b) a flow generating system for generating a flow of the ozone-containing gas in a direction substantially opposite to the first direction.
According to a further feature of the present invention, there is also provided a catalytic filter associated with the container for removing ozone from the ozone-containing gas prior to opening of the container.
There is also provided according to the teachings of the present invention, a method for batch treatment of a product with a potentially harmful gas, the method comprising: (a) providing first and second treatment chambers; (b) treating a first batch of the product with a quantity of the gas within the first treatment chamber; (c) positioning a second batch of the product within the second treatment chamber; and (d) transferring from the first treatment chamber to the second treatment chamber at least part of the quantity of the gas.
According to a further feature of the present invention, the potentially harmful gas is an ozone-containing gas.
According to a further feature of the present invention, the transferring is performed through an ozone generator so as to further increase a proportion of ozone in the ozone-containing gas.
According to a further feature of the present invention, gas is also transferred from the second treatment chamber to the first treatment chamber through a catalytic filter.
According to a further feature of the present invention, pressure-waves are also generated within the first treatment chamber so as to enhance effectiveness of the ozone treatment.
According to a further feature of the present invention, prior to the treatment, at least a surface layer of the product is cooled sufficiently to cause condensation of ozone-containing water vapor on the surface layer.
According to a further feature of the present invention, prior to the treatment, at least a surface layer of the product is cooled sufficiently to cause freezing of ozone-containing water vapor on the surface layer.
According to a further feature of the present invention, the first and second treatment chambers share a common dividing wall which features at least one ozone generator and at least one catalytic filter.
According to a further feature of the present invention, the at least one ozone generator has an inlet switchably communicating with either the first or the second treatment chamber and an outlet switchably communicating with either the first or the second treatment chamber.
According to a further feature of the present invention, the at least one catalytic filter has an inlet switchably communicating with either the first or the second treatment chamber and an outlet switchably communicating with either the first or the second treatment chamber.
There is also provided according to the teachings of the present invention, a high concentration frame-type ozone generator comprising: (a) a plurality of elongated electrodes deployed in substantially parallel, spaced relation to each other so as to form a substantially flat electrode array; (b) a casing substantially enclosing the electrode array, the casing having an inlet and an outlet; and (c) a flow system associated with the casing configured to generate: (i) a recirculating flow of gas within the casing recirculating through the electrode array, and (ii) a through-flow of gas in through the inlet and out through the outlet, the through-flow having a volumetric flow rate significantly less than a volumetric flow rate of the recirculation flow.
According to a further feature of the present invention, the volumetric flow rate of the recirculation flow is at least ten times greater than the volumetric flow rate of the through-flow.
According to a further feature of the present invention, there is also provided a cooling system associated with the casing for cooling the casing.
According to a further feature of the present invention, there is also provided at least one additional electrode array similar to, and deployed parallel to, the electrode array such that the recirculation flow passes sequentially through the electrode array and the additional electrode array.